But according to many academics, industry claims about whiteboards are not based on rigorous academic studies. One frequently cited study, conducted by Marzano Research Laboratory and funded by Promethean, surveyed 85 teachers who volunteered to teach a lesson of their choice to two classes, one with the whiteboard, one without. The teachers then gave a test of their own design, with results showing an average 17-point gain in classrooms with whiteboards. "It's a suggestive study -- you can't conclude anything," said Steve Ross, an education professor at Johns Hopkins University. "And that's being generous."